Okay kiddo, imagine if you had a book that your whole family liked to read, and you loved to read it too. But then one day you found out that some people thought that there was another version of that book, in a completely different language, that your family might have also loved.
That's kind of like what the Hebrew Gospel Hypothesis is. Some people think that there might be another version, or versions, of the story of Jesus from a long time ago, that were originally written in Hebrew. This is different from the version that most people know, which is in Greek.
Some people think that the Hebrew versions might be older and more authentic than the Greek versions. People have been studying and arguing about this for a long time.
It's sort of like a big puzzle or mystery that people are trying to solve. They are looking for clues in old books and writings, trying to put together the pieces to see if there really were Hebrew versions of the story of Jesus.
Does that make sense, little one?